Abstract

The authors have measured noise in thin-film superconducting coplanar waveguide resonators. This noise appears entirely as phase noise, equivalent to a jitter of the resonance frequency. In contrast, amplitude fluctuations are not observed at the sensitivity of their measurement. The ratio between the noise power in the phase and amplitude directions is large, in excess of . These results have important implications for resonant readouts of various devices such as detectors, amplifiers, and qubits. They suggest that the phase noise is due to two-level systems in dielectric materials.

Received 20 September 2006Accepted 01 February 2007Published online 08 March 2007

Acknowledgments:

The authors thank Sunil Golwala, Kent Irwin, Andrew Lange, Konrad Lehnert, John Martinis, and Harvey Moseley for useful discussions. This work was supported in part by the NASA Science Mission Directorate, JPL, Gordon and Betty Moore Foundation, and Alex Lidow, a Caltech Trustee.